First of all, A special thanks to Flavor for his help and his patience

The idea about this project is to combine all additional features you could need on a handheld machine but keeping modification on the motherboard as low as possible, Note: this is intended to work on the Freeplay CM3 platform.

The PCB borders, headers position, CPU heatsink clearance and L2/R2 switches positions are the same.
This addon board embed a USB Nanohub with 2 ports, a BL-R8188FU3 WiFi module (RTL8188FTV with IPEX connector), a DS3231M RTC chip, 3 MCP3021A ADC chips (2 chips for the the Joystick and one for the battery monitoring), a 16x16x4.5 fan (the same used in the original addon board).

Due to USB hub and WiFi module needing to be in the USB header side, the fan position has been switch to the other side of the CPU heatsink but because of this the hotkey switch needed to be moved as well.
A AMS1117-3.3 is used to power the WiFi module and the 2 ADC chips reading the joystick position.

Following recommendation from Flavor, the ADC chip used to monitor battery voltage is running at 4.5v using a MAX6107 voltage reference chip.
The battery voltage also feed the VBAT pin on the RTC chip, the power consumption when the console is off is negligible.

The fan is still controlled with pin 40 using a NPN transistor.

I own a CNC milling machine and all milling bits for this kind of project, machining the PCB with a 0.2mm engraving bits take arround 5 hours. I can only solder components using soldering iron (not hot air or other process) so soldering and checking continuity during this build took me about 4 hours.
I am not really good with PCB design softwares so I falled back to the software I known for CNC machining : Cambam, anything need to be drawn by hand, if you move a component you need to update any traces that goes to it one by one so it was kind of a pain.